The present disclosure relates to a power amplifier module. A mobile terminal that uses a communication network for cellular phones includes a power amplifier module having multiple stages of amplifiers for amplifying power of a radio frequency (RF) signal to be transmitted to a base station. For example, Japanese Unexamined Patent Application Publication No. 2006-180151 discloses a power amplifier module in which a comparatively low cost laterally diffused metal-oxide-semiconductor field-effect transistor (LDMOSFET) is used for a drive stage and a comparatively high efficiency heterojunction bipolar transistor (HBT) is used for a power stage.
In a power amplifier module, typically, a matching network is disposed between an output terminal of the drive stage and an input terminal of the power stage for matching the output impedance of the drive stage and the input impedance of the power stage. Impedance matching between different semiconductor chips may not result in the realization of the desired impedance due to a change in the ground condition of each semiconductor chip, depending on the arrangement positions of the semiconductor chips, and so on, which hinders high-accuracy impedance matching. Due to this problem, the module disclosed in Japanese Unexamined Patent Application Publication No. 2006-180151 has a problem in that the absence of high-accuracy impedance matching between stages of amplifiers results in an increase in the transmission loss of an RF signal.